netdev - Re: Connection tracking and vlan

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Date:	Mon, 2 Nov 2009 11:14:02 -0500
From:	Adayadil Thomas <adayadil.thomas@...il.com>
To:	Ben Greear <greearb@...delatech.com>
Cc:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	netdev@...r.kernel.org, Patrick McHardy <kaber@...sh.net>
Subject: Re: Connection tracking and vlan

If the vlan id is used for hash, it still may not avoid the problem completely,
i.e. in case of both connections hashing to the same bucket.

I was wondering about your opinion about adding an optional member to the tuple
structure, vid (for vlan id).

I have attached the patch for this change. I would be grateful for any comments
such as dependencies on the rest of the system.


Thanks much



On Fri, Oct 30, 2009 at 6:25 PM, Ben Greear <greearb@...delatech.com> wrote:
> On 10/30/2009 04:15 PM, Eric W. Biederman wrote:
>
>>> If ip_conntrack does not consider vlans, it is possible that all 5
>>> tuple are the same
>>> and thus affect the connection tracking.
>>>
>>> I hope I have described the scenario well. If not I can explain in a
>>> more detailed fashion.
>>
>> Unless you have multiple network namespaces linux assumes all packets are
>> in the same ip space.  And 10.10.10.1 is the same machine no matter
>> which interface you talk to it on.
>
> It only takes a relatively small patch that lets conn-track hash on a
> skb->foo_mark, and allow that mark to be set on incoming packets
> based on netdevice or whatever, (before the conn-track lookup is
> done).
>
> This is logically somewhat similar to using multiple routing
> tables and has been working well for me for several years....
>
> Thanks,
> Ben
>
> --
> Ben Greear <greearb@...delatech.com>
> Candela Technologies Inc  http://www.candelatech.com
>
>

View attachment "patch.txt" of type "text/plain" (6804 bytes)